Enterprise Integration Patterns: Designing, Building, and Deploying Messaging Solutions (Addison-Wesley Signature Series (Fowler))

by Hohpe Gregor

Some large enterprises use more than one messaging infrastructure. Thus, a message may have to be routed across messaging systems using a Messaging Bridge (133). Each messaging system is likely to have different requirements for the format of the message body as well as the header. This scenario is another case where we can learn by looking at existing TCP/IP-based network protocols. In many cases, connectivity to another system is restricted to a specific protocol, such as Telnet or Secure Shell (ssh). In order to enable communication using another protocol (for example, FTP), that protocol format has to be encapsulated into packets that conform to the supported protocol. At the other end, the packet payload can be extracted. This process is called tunneling.